Catch _all_ multipart NextPart() errors

internal/upload/rewrite.go

@@ -84,9 +84,12 @@ func rewriteFormFilesFromMultipart(r *http.Request, writer *multipart.Writer, te
 
 	for {
 		p, err := reader.NextPart()
+		if err != nil {
 			if err == io.EOF {
 				break
 			}
+			return cleanup, err
+		}
 
 		name := p.FormName()
 		if name == "" {
@@ -105,6 +108,7 @@ func rewriteFormFilesFromMultipart(r *http.Request, writer *multipart.Writer, te
 			return cleanup, err
 		}
 	}
+
 	return cleanup, nil
 }